Synchronizing apparatus for phototelegraphy



Aug. 25, 1936. A. G. CQOLEY 2,052,383

SYNCITIBONIZING APPARATUS FOR PHOTOTELEGRAPHY Original Filed Dec. 11, 1924 7 1 I I l I l AusTns zJiEY 491,? #314? A ORNEY Patented Aug. 25, 1936 2,052,383 SYNCHBONIZING srrsmrus ron rno'romncmnr Austin a. Cooley, New York, N. Y., mar, by

mesne assignments, to

Radio Corporation of America, a corporation-of Delaware Original application December 11,

Patent No. 2,015,742,

1m, Serial dated October 1, 1935. Divided and this application March 11, 1931, Serial No. 521,665

11 Claims.

ing current, the transmitter being driven at arate proportional to a power frequency, the subject-matter being transmitted by varying the amplitude of the aforesaid current or power; and apparatus for operating the receiver apparatus at a speed proportional to the frequency oi. said current or power together with means for applying so driving forces to the receiver independently of the transmitted power.

In a more specific-aspect the invention comprises apparatus for sending with alternating or other pulsating current, the transmitting carrier or transmitter being driven by the source of the current energy or otherwise at a rate proportional to the frequency of the current and the subject-matter being transmitted by varying the pulsating current, apparatus for driving the receiving carrier or receiver at a speed proportional to said frequency and therefore in synchronism with the transmitting carrier, motive means for a plying driving force to the receiver independently of the pulsating transmitting current, and regulating means responsive to the impulses of said pulsating current for synchronizing the receivers with the current frequency and therefore with the transmitter. Said motive means, which may be an electric motor or other motor, pref- 4o erabiy applies to the receiving carrier an approximately constant driving force sufiicient to overcome its average resistance, and said regulating means therefore requires only a small amount of energy to synchronize the carrier. 45 when the regulating means is in the form of a coil inductively associated with the rotor of said motor or with an associated rotor it functions as motive means to apply advancing force when the receiver tends to lag and to apply retarding force 50 when the'receiver tends to move too fast, the

coil deriving its energy from said pulsating transmitting current or current controlled thereby. For the purpose of illustration one concrete embodiment of the genus of the invention is and shown-diagrammatically in the accompanying drawing in which- Fig. 1 indicates the transmitting apparatus;

Fig. 2 indicates the receiving apparatus. 5

In the particular embodiment of the invention chosen for the purpose of illustration the transmitting apparatus comprises a drum I upon which the photograph, printed matter or the like, is wrapped, a motor 2 for rotating the drum 1 through gears 3 and 4, the drum threading axially on a stationary shaft 5 as it rotates, a generator I for supplying alternating current to variable transformer 1 at a suitable frequency (say 1000 cycles or higher) which is proportional to the speed of drum I, a photo-electric cell 8, a light source 8, lenses II and ii for focusing upon said cell through apertured plate I! a pencil of light reflected from the photograph or the like, an audion I! having its grid H and cathode ll connected to. said cell through an input circuit ll containing a source of potential l1, and having its cathode and anode l8 connected to an output circuit is containing a variable source 20, and an amplifier Al interposed in the output circuit. This amplifier, as well as the amplifiers hereinafter referred to, maybe of audion or other suitable type. The transformer I is connected across the input circuit it by circuit 2i containing a low capacity (e. g. 0.00001 mf) condenser 21, or high resistance 22', (e. g. of the order of five to twenty-five megohms, preferably the latter, depending on the type of audion, etc.)

The receiving apparatus shown in Fig. 2 comprises a drum 23 which rotates without endwise progression, this drum carrying sensitized paper or other suitable recording media. Connected to the drum through gears 14 and Il is a threaded shaft 26 along which travels'a head 21, the head having an opening to receive stationary rod 28 which restrains the head from turning with the shaft. Head 21 carries a needle 28 for directing an electronic discharge to the sheet wound on drum". 'I'hisdlschargeisproducedbyan oscillating circuit 8| feeding into circuit Ii containing coil 32 and condenser 33, the oscillating circuit being controlled by the aforesaid transmitting station working through ampliners A! and Al and a modulator 84.

The oscillator comprises a circuit ll connected to the grid 36 and anode 31 of audion SI and containing battery 88, condenser II and coil ll, the latter being inductively associated with coil 32. The output circuit II from the cathode II andanodellofmodulatorNiscmnectedbetween the coil 4! and cathode 45 of audion 3% the grid 45 of the modulator being connected to amplifier A4, through transformer 43. A condenser 48 may be connected in the circuits by switch 49 but is ordinarily not required.

Geared to the drum 23 is a shaft 48 carrying a conducting disk 49 and geared to shaft 48 is a shaft 50 carrying a conicalrotor 5i of paramagnetic material, the rotor having peripheral poles 52 and an axial stem 53 fast to shaft 50. Stationary coils 54 and 55 are associated with the poles 52 and stem 53 respectively, the coil 55 being energized by battery 56 to polarize poles 52 and also to pull upwardly on stem 53 thereby to cause the shaft 50 to rest lightly on bearing 51. The coils 54 are connected to amplifier A3 through circuit 58 containing switch 59. Associated with disk 49 are electro-magnets 60 connected to a variable source of alternating current 6| through circuit 62 containing condenser 63 to throw magnets 60 out of phase with each other and switch 64. The circuit 58 may also be con- .nected to electro-magnets associated with disk 49 and in the drawing this circuit is connected to electro-magnets 65 other than magnets 60 through circuit 66 containing switch 57, a con denser 75 being connected in series with one of the electro-magnets 65 to produce the necessary phase displacement.

In transmitting, motor 2 drives the drum i at a speed proportional to the frequency of the alternating current from generator ii and the light from source 9 traces a spiral around the periphery of the drum as the latter is threaded along shaft 5. The alternating current from generator 6, acting upon the grid of audion l3, causes pulsations of impulses to be transmitted from the transmitting station to the receiving station, either by wire or by radio. The light reflected from the subject-matter on drum l to the photo-electric cell varies the resistance of circuit IS in accordance with variations in the reflection ability of the successive points of the subject-matter. This variation of resistance in circuit 56 varies the potential on grid l4 and thereby varies the aforesaid impulses.

It has been found that by varying the potential of battery 28 either like or opposite reproduction can be effected, that is, either a positive or 2.

- negative can. be produced at the receiving station when using a negative (or a positive) at the transmitting station. For example, like reproduction has been attained with twenty volts and opposite reproduction with ten volts. This is due to the fact that under the respective conditions opposite eflects are produced-by the pulsating potential impressed upon grid ill by transformer 7 when the plate potential is varied, A

' theory explanatory of this mode of operation is of the modulator is sumcient to prevent oscil= lations or at least render the oscillations so feeble as to be ineffective. .When an impulse is acting upon grid- 55 the resistance is lowered sufiiciently to permit oscillations, the intensity of the oscillations being proportional to the intensity of the impulse. The oscillating circuit tion, a. system in which the subject-matter is sent of high-frequency and high-potential adapted to produce an electronic discharge (e. g. a corona discharge) from needle 29 when above a predetermined intensity higher than that existing 5 between successive impulses, the intensity of the discharge depending upon the excess of oscillation intensity above the predetermined intensity, whereby an electronic discharge is emitted. from needle 29 during each impulse (except perhaps 10 while recording a white or an extremely light representation on the receiving paper). Thus, in transmitting a half-tone, a dot (or short dash) is recorded on the receiving paper at each impulse, the dot varying in intensity in response 15 to variations in the intensity of said impulses, and in transmitting extreme contrasts such as the black and white of printed matter, at each impulse during passage of black or white (depending upon the adjustment of the transmit- 20 ting apparatus as above described) past the point of incidence of the light from source 9.

The recording paper may be of the type requiring development subsequent to exposure by the electronic discharge to convert the latent 25 image into a patent image or it may be of the type in which a patent image is produced without development, the latter type having the advantage of displaying the image as it is recorded. The electronic discharge produces the exposure as 30 a result of its light and/or heat and/or electronicv bombardment of the photographic emulsion.

The receiving drum 23 is driven at approximately the speed of the transmitting drum l by the eddy-current motor comprising disk 49, the

current in coils 60 being adjusted to such quantity and phase relation as to overcome the average resistance of the parts driven thereby, and

the aforesaid impulses of current synchronize the drum 23 with drum I by recurrently energizing magnets 56 at the frequency of the transmitting current. The poles 52 are so distributed that one pole passes each magnet 54 during each impulse; If the motor 39 is driving the drum 23 at synchronous speed the alternate advancing and retarding effects of the magnets 54 cancel, whereas if motor 9 tends to drive drum 23 too slow ortoo fast either the advancing or the retarding effect of magnets 55 predominates to maintain the drum in synchronism.

By closing s itch 3? power is supplied to motor 59 in proportion to the intensity of the transmitting impulses, and the power of the eddy-current motor is thereby in accordance with the current synchronous motor iii-55, thus more effectively holding the drum in synchronism during wide variations in the intensity of the transmitting impulses.

While I have shown for purposes of illustra- 60 by modulating the synchronizing pulsations it will be understood that in its broader aspect the present invention is independent of whether or not the subject-matter is transmitted by modulating these pulsations or other pulsations. For example, a second generator 5' may be connected with the plate circuit I9 through transformer l for producing synchronizing pulsations of different frequency, in which case the receiving apparatus is adjusted to respond to these pulsations and the pulsations produced by generator 6 have no efiect upon the synchronizing apparatus owing to their diiierent frequency. It will also be understood that this invention is applicable to multiplex systems a plunality of images to or signals are sent simultaneously by modulating diil'erent pulsations of diflerent frequencies and/or heat frequencies according to the different subject-matter respectively.

This application is a division of application SerialNo. 755,336, died December 11, 1924.

What is claimed is:

1. Scanning apparatus for television and the like, comprising means for producing a luminous point electrical recording dischargeof relatively high frequency currents, means for causing travel of said discharge in a predetermined scanning pattern, and means for modulating said high frequency currents to control the luminous intensity of said discharge.

2. The method of scanning for television and the like, which comprises producing a self-luminous illuminating point electrical recording discharge by passing. relatively high frequency currents between a pair of spaced and relatively moving electrode systems, and modulating said high frequency currents to control the luminous intensity of said discharge.

3.-The methodof scanning for television and the like, which comprises producing a self-luminous point electrical recording discharge bypassing relatively high frequency currents between a pair of the relatively moving electrode systems,-

producing travel of said discharge in a predetermined path at a predetermined speed, and modulating said high frequency currents to control the luminous intensity of said discharge. 1

4. In an image transmission system the combination of means for transmitting a carrier wave modulated according to shade characteristics of the image, the frequency of said carrier wave being suitable for synchronizing a reproducing light source at the receiver, means at the receiver for changing the received modulated carrier wave into a. similarly modulated high frequency wave for energizing said light source, and means for applying a portion of the received carrier wave to synchronize the receiver with the transmitter.

5. A device for reproducing a visual image comprising a pair of spaced electrodes, one of said electrodes being in the form of a needle point, means for impressing a sustained high frequency wave across said electrodes to produce a discharge at said needle point electrode, and means including a vacuum tube modulator for modulating the amplitude of said high frequency waves under control of received image tor for generating sustained high frequency.

waves, means for impressing the output of said oscillator on said needle point electrode, means to receive image currents, and a vacuum tube modulator for modulating the output of said oscillator under control of the received currents.

8. A system according to claim '7 in which the recording medium is of the type adapted to have the image produced thereon without development under control of the discharge from said needle point electrode.

9. A system of the character described comprising a pair of spaced electrodes, one of which is in the form of a needle point, an image recording surface positioned between said electrodes, means for producing relative movement between said needle point electrode and said recording surface, a vacuum tube oscillator for generating a sustained high frequency wave, means for impressing said wave on said needle point electrode, a vacuum tube modulator for said osscillator, and means for impressing received image currents upon said oscillator-modulator to correspondinglyvary the discharge between said electrodes.

10. A system according to claim 9 in which theneedle point electrode is moved transversely across said recording surface.

11. An image producing system comprising a source of carrier current at a receiving station, means at said station for modulating current from said source in accordance with the received image impulses, and light producing means controlled by said modulated current.

AUSTIN G. COOLEY. 

